ECONOMIC ANALYSIS OF SURGICAL SITE INFECTIONS AFTER CEASARIAN SECTION IN NORWAY

Abstract

ABSTRACT Background: Surgical site infection is a common complication after caesarian section. Correct identification of risk factors for SSI is key to the design and implementation of effective preventive strategies. Preventive strategies are costly, however, and should be implemented up to the point where the costs per surgical site infection avoided are less than the benefits gained per surgical site infection. This means that only cost effective strategies should be embarked on. Objectives: To identify risk factors of surgical site infections and the associated costs and to perform a cost-effectiveness analysis on extending antibiotic prophylaxis to all women undergoing caesarian section in Norway. Study Group: Women who under-went caesarian section in Norway and were captured by the Norwegian surveillance system for hospital-acquired infections (NOIS) between September 2012 and December 2014. Methods: Three analyses (risk analysis, cost analysis and cost-effectiveness analysis) were conducted from a hospital perspective. Logistic regression was used for the risk analysis, micro-costing for the cost analysis and decision analytical model for the cost-effectiveness analysis. Surgical site infection avoided was the measure of effect in cost effectiveness analysis. All costs were in Norwegian kroner (NOK, 2015). Results: A total of 19,796 women who underwent caesarian section were included in the study. The mean age was 31± 4. The rate of surgical site infections was 4.4% or 868 out of 19,796 caesarian sections. Data on 10 variables were analyzed and three of these were identified as independent risk factors of surgical site infections: (i) ASA score greater than III (OR 11.49; p-value 0.05; 95% CI 1.02 – 129.46), (ii) hospitals with bed capacity 250 – 500 (OR 1.44; p-value 0.04; 95% CI 1.01–2.06) and (iii) secondary level hospitals (OR 2.30; p-value 0.00; 95% CI 1.36 – 3.89). The average cost of caesarian section not complicated with SSI was NOK 52,117. For caesarian section complicated with SSI, it was NOK 124,321. The costs of SSI increased with the depth of infection. For superficial SSI, the costs were NOK 97,301, for deep SSI there were NOK 189,329 and for organ/space infections there were NOK 196,754. Prolonged length of stay accounted for 78% of all the costs and the least costs were for laboratory tests. The average cost per patient with the current antibiotic guidelines was NOK 55,634 while it was NOK 55,231 if the antibiotic prophylaxis is given to all women undergoing caesarian section. The proportion of women with SSI was 5% and 4% for the current and extended guidelines respectively, representing a cost saving of NOK 40,300 per avoided SSI. The difference in costs and effects between the extended guidelines and the current guidelines was NOK 403, (95% CI: NOK -900 to NOK150) and 0.01, (95% CI: 0.0025 to 0.012).

ABSTRACT Background: Surgical site infection is a common complication after caesarian section. Correct identification of risk factors for SSI is key to the design and implementation of effective preventive strategies. Preventive strategies are costly, however, and should be implemented up to the point where the costs per surgical site infection avoided are less than the benefits gained per surgical site infection. This means that only cost effective strategies should be embarked on. Objectives: To identify risk factors of surgical site infections and the associated costs and to perform a cost-effectiveness analysis on extending antibiotic prophylaxis to all women undergoing caesarian section in Norway. Study Group: Women who under-went caesarian section in Norway and were captured by the Norwegian surveillance system for hospital-acquired infections (NOIS) between September 2012 and December 2014. Methods: Three analyses (risk analysis, cost analysis and cost-effectiveness analysis) were conducted from a hospital perspective. Logistic regression was used for the risk analysis, micro-costing for the cost analysis and decision analytical model for the cost-effectiveness analysis. Surgical site infection avoided was the measure of effect in cost effectiveness analysis. All costs were in Norwegian kroner (NOK, 2015). Results: A total of 19,796 women who underwent caesarian section were included in the study. The mean age was 31± 4. The rate of surgical site infections was 4.4% or 868 out of 19,796 caesarian sections. Data on 10 variables were analyzed and three of these were identified as independent risk factors of surgical site infections: (i) ASA score greater than III (OR 11.49; p-value 0.05; 95% CI 1.02 – 129.46), (ii) hospitals with bed capacity 250 – 500 (OR 1.44; p-value 0.04; 95% CI 1.01–2.06) and (iii) secondary level hospitals (OR 2.30; p-value 0.00; 95% CI 1.36 – 3.89). The average cost of caesarian section not complicated with SSI was NOK 52,117. For caesarian section complicated with SSI, it was NOK 124,321. The costs of SSI increased with the depth of infection. For superficial SSI, the costs were NOK 97,301, for deep SSI there were NOK 189,329 and for organ/space infections there were NOK 196,754. Prolonged length of stay accounted for 78% of all the costs and the least costs were for laboratory tests. The average cost per patient with the current antibiotic guidelines was NOK 55,634 while it was NOK 55,231 if the antibiotic prophylaxis is given to all women undergoing caesarian section. The proportion of women with SSI was 5% and 4% for the current and extended guidelines respectively, representing a cost saving of NOK 40,300 per avoided SSI. The difference in costs and effects between the extended guidelines and the current guidelines was NOK 403, (95% CI: NOK -900 to NOK150) and 0.01, (95% CI: 0.0025 to 0.012).